Polymorphisms of IRAK1 Gene on X Chromosome Is Associated with Hashimoto Thyroiditis in Korean Children

Autoimmune thyroid disease (AITD) is predominant in females and has been focused on the sexual diploid in immune response. The IL-1 receptor-associated kinase 1 (IRAK1) gene on the X chromosome was recently suggested as strong autoimmune disease-susceptible loci, second to the major histocompatibility complex region. We investigated the frequency of IRAK1 single-nucleotide polymorphisms (SNPs) in children with AITD. In this study, we observed that SNPs of IRAK1 including rs3027898, rs1059703, and rs1059702 in 115 Korean AITD pediatric patients (Graves' disease = 74 [females = 52/males = 22]; Hashimoto disease [HD] = 41 [females = 38/males = 3]; thyroid-associated ophthalmopathy [TAO] = 40 (females = 27/males = 13); without TAO = 75 (females = 63/males = 12); total males = 25, total females = 90; mean age = 11.9 years) and 204 healthy Korean individuals (males = 104/females = 100). The data from cases and controls were analyzed from separate sex-stratified or all combined by χ 2 test for categorical variables and Student t test for numerical variables. Our study revealed that SNPs of IRAK1-associated HD and without TAO but Graves' disease and TAO were not found significant. When cases and controls were analyzed by separate sex, we found that rs3027898 AA, rs1059703 AA, and rs1059702 GG showed disease susceptibility in female AITD, HD, and without TAO. Also, all rs3027898, rs1059703, and rs1059702 were found to be in strong linkage disequilibrium (D' = 0.96-0.98, r2 = 0.83-0.97). The haplotype of 3 SNPs was higher in AITD than in controls (CGA, r2 = 5.42, P = 0.019). Our results suggest that IRAK1 polymorphisms may contribute to the pathogenesis of HD, AITD, and without thyroid-associated ophthalmopathy for females.

Grass carp (Ctenopharyngodon idella) IRAK1 and STAT3 up-regulate synergistically the transcription of IL-10

In vertebrates, IL-10 is an anti-inflammatory factor that serves as a key inhibitory role in a wide range of immune responses. IRAK1 (IL-1 receptor-associated kinase 1), a key molecule in the inflammatory signal of IL-1R/TLR, plays an important pivotal role in regulating the autoimmunity of body. STAT3 (Signal transducer and activator of transcription 3) activated by IRAK1 participates in inflammation, tumorigenesis, metabolic disorders and immune response. Under the stimulation of LPS, IRAK1 enters the nucleus to form a dimer with STAT3 and regulates the expression of IL-10. However, the relationship between fish IRAK1 and STAT3 has not been reported. To explain the anti-inflammation in fish, we amplified and identified the complete open reading frame of grass carp IRAK1 (CiIRAK1) and STAT3 (CiSTAT3) based on the existing sequences. The expression of CiIRAK1 and CiSTAT3 were up-regulated significantly under the stimulation of LPS. This result suggests that both CiIRAK1 and CiSTAT3 may be involved in LPS-induced TLR4 pathway. The subcellular localization experiment revealed that CiIRAK1 is distributed in cytoplasm and enters nucleus after LPS stimulation. CiSTAT3 is distributed in both cytoplasm and nucleus with or without LPS stimulation. Immunoprecipitation assay revealed that CiIRAK1 interacted with CiSTAT3 under LPS stimulation. However in absence of LPS stimulation, CiIRAK1 and CiSTAT3 cannot interact with each other. Subsequently, immunofluorescence colocalization experiment further proved the interaction of CiIRAK1 and CiSTAT3 in nucleus under LPS stimulation. The dual luciferase reporter assays indicated that the binding of CiIRAK1 and CiSTAT3 synergistically enhanced the activity of CiIL-10 promoter.

Molecular features of interleukin-1 receptor-associated kinase-b and a in Mytilus coruscus, regulating their function by infection of aquatic pathogens and the expression of their serine/threonine protein kinase functional domains

Interleukin-1 receptor-associated kinases (IRAKs) play important roles in the innate immune system of TLR (Toll-like receptor) signaling pathway. In this paper, interleukin-1 receptor-associated kinase-b (designated as McIRAK-b) and interleukin-1 receptor-associated kinase-a (named as McIRAK-a) were obtained based on the transcriptome data, the full length of McIRAK-b was 1815 bp and McIRAK-a was 3168bp, encoding 532 and 978 amino acids, respectively. BLASTp analysis and phylogenetic relationship strongly suggested that the deduced amino acid sequence of McIRAK-b had high homology with IRAK-4 and McIRAK-a was similar to IRAK-1 of other mollusks, especially at their function domains. The expressions of McIRAK-b and McIRAK-a were detected in six tissues including adductor muscle, hemocyte, gills, gonad and hepatopancreas, and the highest expressions appeared both in gills. The expressions of McIRAK-b and McIRAK-a in gills were observed with time-dependent manners after bacterial infections. After being challenged with Vibrio alginolyticus, McIRAK-b expressed significantly and got the peak at 8 h (9.47 times compared with the control group), but the peak appeared at 4 h by being infected with Vibrio parahaemolyticus (12.02 times compared with the control group). The highest point of McIRAK-a mRNA appeared at 12 h (5.16 times) after being challenged with V.alginolyticus and 8 h (4.21 times) for V.parahaemolyticus challenge. The results suggested that IRAK-b and IRAK-a might be important in immune signaling pathway of mussels. The kinase functional domain sequences (S_TKc) of McIRAK-b and McIRAK-a expressed in BL21(DE3) and purified by Ni-NAT Superflow resin conforming to the expected molecular weight with many active sites for their conferring protein-protein interaction functions. This study may provide some further understandings of the regulatory mechanisms in the bivalve innate immune system for IRAKs family.

lncRNA NEAT1 mediates sepsis progression by regulating Irak2 via sponging miR-370-3p

Sepsis is a life-threatening condition and often associated with multiple organ failure. Nuclear-enriched abundant transcript 1 (NEAT1), a member of the long non-coding RNAs (lncRNAs), was reported to be involved in the regulation of sepsis progression. However, its precise regulatory mechanism needs to be further explored. In this study, the cell-counting kit-8 assay was used to check cell viability. The quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect the expression levels of NEAT1, miR-370-3p and Interleukin 1 receptor associated kinase 2 (Irak2). Flow cytometry assay and ELISA were used to check cell apoptosis and the concentrations of inflammatory cytokines, respectively. The starBase was used to predict binding sites between miR-370-3p and NEAT1 or Irak2 and the dual-luciferase reporter assay was performed to verify the interaction. The protein level of Irak2 in samples was measured by western blot. The high concentration of lipopolysaccharide (LPS) led to the high death ratio of RAW 264.7 and HL-1 cells. NEAT1 and Irak2 were upregulated in sepsis tissues and LPS-induced RAW 264.7 and HL-1 cells, opposite to the expression of miR-370-3p. In addition, knockdown of NEAT1 promoted viability, suppressed apoptosis and reduced the expression of inflammatory cytokines in LPS-induced RAW 264.7 and HL-1 cells. Moreover, we found that miR-370-3p interacted with NEAT1 and targeted the 3'UTR of Irak2. Further research indicated that downregulation of miR-370-3p or upregulation of Irak2 rescued NEAT1 silencing-mediated inhibitory effect on sepsis progression. Knockdown of NEAT1 hampered sepsis progression by downregulating Irak2 via interacting with miR-370-3p in LPS-induced RAW 264.7 and HL-1 cells.

Induction of IRAK-M in melanoma induces caspase-3 dependent apoptosis by reducing TRAF6 and calpastatin levels

Melanoma represents the most serious type of skin cancer. Although recent years have seen advances using targeted and immunotherapies, most patients remain at high risk for tumor recurrence. Here we show that IRAK-M, a negative regulator of MyD88 signaling, is deficient or low in melanoma and expression levels correlate with patient survival. Inducing IRAK-M expression using genetic approaches or epigenetic modifiers initiates apoptosis by prompting its interaction with TRAF6 via IRAK-M's C-terminal domain. This complex recruits and degrades calpastatin which stimulates calpain activity and triggers caspase-3-dependent but caspase-8,-9-independent apoptosis. Using a drug screen, we identified compounds that induced IRAK-M expression. Administration of IRAK-M-inducing drugs reduced tumor growth in mice but was ineffective against IRAK-M knock-down tumors. These results uncover a previously uncharacterized apoptosis pathway, emphasize IRAK-M as a potential therapeutic target and suggest that the anticancer activity of certain drugs could do so through their ability to induce IRAK-M expression.

IRAK1 Is a Critical Mediator of Inflammation-Induced Preterm Birth

Preterm birth (PTB) is a major cause of neonatal mortality and morbidity, often triggered by chorioamnionitis or intrauterine inflammation (IUI) with or without infection. Recently, there has been a strong association of IL-1 with PTB. We hypothesized that IL-1R-associated kinase 1 (IRAK1), a key signaling mediator in the TLR/IL-1 pathway, plays a critical role in PTB. In human fetal membranes (FM) collected immediately after birth from women delivering preterm, p-IRAK1 was significantly increased in all the layers of FM with chorioamnionitis, compared with no-chorioamnionitis subjects. In a preterm rhesus macaque model of IUI given intra-amniotic LPS, induction of p-IRAK1 and downstream proinflammatory signaling mediators were seen in the FM. In a C57BL/6J wild-type PTB mouse model of IUI given intrauterine LPS, an IRAK1 inhibitor significantly decreased PTB and increased live birth in a dose-dependent manner. Furthermore, IRAK1 knockout mice were protected from LPS-induced PTB, which was seen in wild-type controls. Activation of IRAK1 was maintained by K63-mediated ubiquitination in preterm FM of humans with chorioamnionitis and rhesus and mouse IUI models. Mechanistically, IRAK1 induced PTB in the mouse model of IUI by upregulating expression of COX-2. Thus, our data from human, rhesus, and mouse demonstrates a critical role IRAK1 in IUI and inflammation-associated PTB and suggest it as potential therapeutic target in IUI-induced PTB.

Interleukin-1 Receptor-Associated Kinase (IRAK) Signaling in Kaposi Sarcoma-Associated Herpesvirus-Induced Primary Effusion Lymphoma

Kaposi sarcoma-associated herpesvirus (KSHV) is necessary but not sufficient for primary effusion lymphoma (PEL) development. Alterations in cellular signaling pathways are also a characteristic of PEL. Other B cell lymphomas have acquired an oncogenic mutation in the myeloid differentiation primary response 88 (MYD88) gene. The MYD88 L265P mutant results in the activation of interleukin-1 receptor associated kinase (IRAK). To probe IRAK/MYD88 signaling in PEL, we employed CRISPR/Cas9 technology to generate stable deletion clones in BCBL-1Cas9 and BC-1Cas9 cells. To look for off-target effects, we determined the complete exome of the BCBL-1Cas9 and BC-1Cas9 cells. Deletion of either MYD88, IRAK4, or IRAK1 abolished interleukin-1 beta (IL-1β) signaling; however, we were able to grow stable subclones from each population. Transcriptome sequencing (RNA-seq) analysis of IRAK4 knockout cell lines (IRAK4 KOs) showed that the IRAK pathway induced cellular signals constitutively, independent of IL-1β stimulation, which was abrogated by deletion of IRAK4. Transient complementation with IRAK1 increased NF-κB activity in MYD88 KO, IRAK1 KO, and IRAK4 KO cells even in the absence of IL-1β. IL-10, a hallmark of PEL, was dependent on the IRAK pathway, as IRAK4 KOs showed reduced IL-10 levels. We surmise that, unlike B cell receptor (BCR) signaling, MYD88/IRAK signaling is constitutively active in PEL, but that under cell culture conditions, PEL rapidly became independent of this pathway.IMPORTANCE One hundred percent of primary effusion lymphoma (PEL) cases are associated with Kaposi sarcoma-associated herpesvirus (KSHV). PEL cell lines, such as BCBL-1, are the workhorse for understanding this human oncovirus and the host pathways that KSHV dysregulates. Understanding their function is important for developing new therapies as well as identifying high-risk patient groups. The myeloid differentiation primary response 88 (MYD88)/interleukin-1 receptor associated kinase (IRAK) pathway, which has progrowth functions in other B cell lymphomas, has not been fully explored in PEL. By performing CRISPR/Cas9 knockout (KO) studies targeting the IRAK pathway in PEL, we were able to determine that established PEL cell lines can circumvent the loss of IRAK1, IRAK4, and MYD88; however, the deletion clones are deficient in interleukin-10 (IL-10) production. Since IL-10 suppresses T cell function, this suggests that the IRAK pathway may serve a function in vivo and during early-stage development of PEL.

Molecular characterization, expression and functional analysis of IRAK1 and IRAK4 in Nile tilapia (Oreochromis niloticus)

Interleukin-1 receptor-associated kinase 1 (IRAK1) and IRAK4 are critical signalling mediators and play pivotal roles in the innate immune and inflammatory responses mediated by TLR/IL-1R. In the present study, two IRAK family members, OnIRAK1 and OnIRAK4, were identified in the Nile tilapia Oreochromis niloticus with a conserved N-terminal death domain and a protein kinase domain, similar to those of other fishes and mammals. The gene structures of OnIRAK1 and OnIRAK4 are organized into fifteen exons split by fourteen introns and ten exons split by nine introns. OnIRAK1 and OnIRAK4 were broadly expressed in all of the tissues tested, with the highest expression levels being observed in the blood and the lowest expression levels being observed in the liver. Both genes could be detected from 2 d post-fertilization (dpf) to 8 dpf during embryonic development. Moreover, the expression levels of OnIRAK1 and OnIRAK4 were clearly altered in all five tissues after Streptococcus agalactiae infection in vivo and could be induced by LPS, Poly I: C, S. agalactiae WC1535 and △CPS in Nile tilapia macrophages. The overexpression of OnIRAK1 and OnIRAK4 in 293T cells showed that they were both distributed in the cytoplasm and could significantly increase NF-κB activation. Interestingly, after transfection, OnIRAK1 significantly upregulated OnMyd88-induced NF-κB activation, while OnIRAK4 had no effect on OnMyd88-induced NF-κB activation. Co-immunoprecipitation (Co-IP) assays showed that OnMyd88 did not interact with either OnIRAK1 or OnIRAK4 and that OnIRAK1 did not interact with OnIRAK4. Taken together, these findings suggest that OnIRAK1 and OnIRAK4 could play important roles in TLR/IL-1R signalling pathways and the immune response to pathogen invasion.

Molecular characterization and expressional modulation of IRAK1 as downstream signaling adaptor molecule of TLR-signaling pathways in Labeo rohita following PAMPs stimulation and bacterial infections

Interleukin-1 receptor associated kinase (IRAK1) is one of the crucial signal transduction mediators in TLR/IL-1R signaling pathways in host immune system. To investigate about it in rohu (Labeo rohita), one of the economically important freshwater fish species in the Indian subcontinent, we cloned, characterized and analyzed its expression following bacterial infection and pathogens associated molecular patterns (PAMPs) stimulation. The full-length cDNA of rohu IRAK1 (LrIRAK1) consisted of 2765 nucleotide (nt) having an ORF of 2115 nt encoding a polypeptide of 704 amino acids (aa) with a molecular mass of 70.4 kDa. Structurally, LrIRAK1 consisted of twenty-nine helix, twelve strands and forty one coils making one N-terminal death domain (19-94 aa) and a central serine threonine kinase catalytic domain (or kinase domain) (188-489aa). In addition to these two prominent domains, LrIRAK1 also contained highly conserved amino acids viz., lysine ²¹⁵ and aspartic acid ³¹⁴ and threonine ^{185, 361} which were reported to be important for kinase and phosphorylation activity respectively in other animals. Similar to higher vertebrates, LrIRAK1 also consisted of CDK1 (cyclin-dependent kinase1) at 338-352 aa; NEK2 (NIMA-related kinase 2) at 47-61 aa; NEK6 (NIMA-related kinase 6) at 581-595 aa and AMPK (AMP- activated protein kinase) motif at 518-538 aa. Phylogenetically, LrIRAK1 is closely related to cave fish, common carp exhibiting high similarity (~95%) and identity (~90%). In the uninfected fish, the LrIRAK1 expression was highest in liver (~11.5 fold) and lowest in blood. In response to Aeromonas hydrophila, Edwardsiella tarda and Bacillus subtilis infection and various TLR and NLR-ligands stimulation, the expression of LrIRAK1 was markedly enhanced at various time points in almost all the tested tissues. These results together suggest the key role of LrIRAK1 in pattern recognition receptors (PRRs)-mediated host defense against pathogenic insults.

IRAK3 modulates downstream innate immune signalling through its guanylate cyclase activity

Interleukin-1 receptor associated kinase 3 (IRAK3) is a cytoplasmic homeostatic mediator of inflammatory responses and is potentially useful as a prognostic marker in inflammation. IRAK3 inhibits signalling cascades downstream of myddosome complexes associated with toll like receptors. IRAK3 contains a death domain that interacts with other IRAK family members, a pseudokinase domain and a C-terminus domain involved with tumour necrosis factor receptor associated factor 6 (TRAF6). Previous bioinformatic studies revealed that IRAK3 contained a guanylate cyclase centre in its pseudokinase domain but its role in IRAK3 action is unresolved. We demonstrate that wildtype IRAK3 is capable of producing cGMP. Furthermore, we show that a specific point mutation in the guanylate cyclase centre reduced cGMP production. Cells containing toll like receptor 4 and a nuclear factor kappa-light-chain-enhancer of activated B cells (NFĸB) reporter system were transfected with IRAK3 or mutant IRAK3 proteins. Cell-permeable cGMP treatment of untransfected control cells suppresses downstream signalling through modulation of the NFĸB in the presence of lipopolysaccharides. Cells transfected with wildtype IRAK3 also suppress lipopolysaccharide induced NFĸB activity in the absence of exogenous cGMP. Lipopolysaccharide induced NFĸB activity was not suppressed in cells transfected with the IRAK3 mutant with reduced cGMP-generating capacity. Whereas in the presence of exogenously applied cell-permeable cGMP the IRAK3 mutant was able to retain its function by suppressing lipopolysaccharide induced NFĸB activity. Furthermore, increasing the amount of membrane permeable cGMP did not affect IRAK3's ability to reduce NFĸB activity. These results suggest that cGMP generated by IRAK3 may be involved in regulatory function of the protein where the presence of cGMP may selectively affect downstream signalling pathway(s) by modulating binding and/or activity of nearby proteins that interact in the inflammatory signalling cascade.

Aberrant methylation of host macrophages induced by tuberculosis infection

DNA methylation has been introduced as a promising biomarker for different diseases. Alterations in macrophage DNA methylation status have been documented during Mycobacterium tuberculosis (Mtb) infection. We conducted this study using a human methylation PCR array kit, which comprised a panel of 22 genes in TLR2 signaling pathway, in order to gain insights into epigenetic interactions between drug-susceptible and -resistant Mtb strains and THP-1-derived macrophages (one of the main host immunity cells during TB infection). We also evaluated the expression of Rv1988 gene in the studied isolates. It was found that the methylation level of all of the studied inflammatory genes, except Irak-2 and Tbk-1, increased in THP-1 macrophages, which were infected by extensively drug-resistant (XDR) Mtb strains, compared with the mock cells (P < 0.05). In susceptible strains, we only found hypomethylation in Irak-2 gene, in addition to a slight increase in the methylation levels of Ubev, Ube2n, and Traf6 genes. The present findings provide new insights into the potential role of resistant and susceptible Mtb strains in promoting aberrant epigenetic modifications in macrophages. Further investigations on the host epigenomes, infected with different Mtb isolates, are needed to elucidate their functions in immunological responses and to introduce new effective tools against Mtb infection.

Putative link between Polo-like kinases (PLKs) and Toll-like receptor (TLR) signaling in transformed and primary human immune cells

Toll-like receptors (TLRs) are important sentinels of bacterial and viral infection and thus fulfil a critical sensory role in innate immunity. Polo-like kinases (PLKs), a five membered family of Ser/Thr protein kinases, have long been studied for their role in mitosis and thus represent attractive therapeutic targets in cancer therapy. Recently, PLKs were implicated in TLR signaling in mice but the role of PLKs in TLR signaling in untransformed primary immune cells has not been addressed, even though PLK inhibitors are in clinical trials. We here identified several phospho-serine and phospho-threonine residues in the known TLR pathway kinases, Interleukin-1 receptor-associated kinase (IRAK) 2 and IRAK4. These sites lie in canonical polo-box motifs (PBM), sequence motifs known to direct recruitment of PLKs to client proteins. Interestingly, PLK1 was phosphorylated and PLK 2 and 3 mRNA induced upon TLR stimulation in primary immune cells, respectively. In whole blood, PLK inhibition disparately affected TLR mediated cytokine responses in a donor- and inhibitor-dependent fashion. Collectively, PLKs may thus potentially interface with TLR signaling in humans. We propose that temporary PLK inhibitor-mediated blockade of TLR-signaling in certain patients receiving such inhibitors during cancer treatment may cause adverse effects such as an increased risk of infections due to a then compromised ability of the TLR recognition system to sense and initiate cytokine responses to invading microbes.

Expression and clinicopathological role of miR146a in thyroid follicular carcinoma

PURPOSE

Dysregulation of microRNA expression has been involved in the development and progression of follicular thyroid carcinoma (FTC). The aim of this work was to study the expression of miRNA146a in FTC and the association with clinicopathological features of the disease.

METHODS

Thirty-eight patients affected by FTC were included in the study. Twenty patients carrying follicular thyroid adenoma (FA) were also enroled as the benign counterpart of FTC. Total RNA including miRNA146a was extracted from formalin-fixed paraffin-embedded (FFPE) pairs of affected/unaffected tissue and its expression was assessed by real-time PCR. Two selected target genes, TRAF6 (tumour necrosis factor receptor-associated factor 6) and IRAK1 (Il-1 receptor-associated kinase 1/2), were also analysed.

RESULTS

miR146a expression in FTC tissue was overall not downregulated in malignant versus unaffected tissue, but its expression was inversely correlated with clinicopathological features of FTCs at diagnosis. A decreased expression of miR146a became apparent in FTC thyroid tissue of widely compared to minimally invasive tumours. However, miR146a expression differences between contralateral unaffected tissue (extra-FTC) and FTC were not observed regardless of clinicopathological features. IRAK1, a known target for miR146a, was upregulated in FTC and the increase was mainly appreciable in Hurtle FTC variant. Unexpectedly, miR146a did not correlate with TRAF6 showing an inverse trend compared to IRAK1 although both genes regulate the activity of nuclear factor- kB (NF-kB).

CONCLUSION

The results of this study indicate that downregulation of miR146a, inversely correlated with clinicopathological features of FTCs at diagnosis and suggest a possible involvement of miR146a in FTC development. IRAK1 over-expression in FTC may be related to tumour development/progression. In vitro experiments are needed to support this hypothesis.

Macrophage subsets exhibit distinct E. coli-LPS tolerisable cytokines associated with the negative regulators, IRAK-M and Tollip

Macrophages (Mϕs) play a central role in mucosal immunity by pathogen sensing and instruction of adaptive immune responses. Prior challenge to endotoxin can render Mφs refractory to secondary exposure, suppressing the inflammatory response. Previous studies demonstrated a differential subset-specific sensitivity to endotoxin tolerance (ET), mediated by LPS from the oral pathogen, Porphyromonas gingivalis (PG). The aim of this study was to investigate ET mechanisms associated with Mφ subsets responding to entropathogenic E. coli K12-LPS. M1- and M2-like Mφs were generated in vitro from the THP-1 cell line by differentiation with PMA and Vitamin D3, respectively. This study investigated ET mechanisms induced in M1 and M2 Mφ subsets, by measuring modulation of expression by RT-PCR, secretion of cytokines by sandwich ELISA, LPS receptor, TLR4, as well as endogenous TLR inhibitors, IRAK-M and Tollip by Western blotting. In contrast to PG-LPS tolerisation, E. coli K12-LPS induced ET failed to exhibit a subset-specific response with respect to the pro-inflammatory cytokine, TNFα, whereas exhibited a differential response for IL-10 and IL-6. TNFα expression and secretion was significantly suppressed in both M1- and M2-like Mφs. IL-10 and IL-6, on the other hand, were suppressed in M1s and refractory to suppression in M2s. ET suppressed TLR4 mRNA, but not TLR4 protein, yet induced differential augmentation of the negative regulatory molecules, Tollip in M1 and IRAK-M in M2 Mφs. In conclusion, E. coli K12-LPS differentially tolerises Mφ subsets at the level of anti-inflammatory cytokines, associated with a subset-specific divergence in negative regulators and independent of TLR4 down-regulation.

Irak-4 rs4251481 gene variant: as a risk factor on inflammatory bowel disease

Background/aim

Abnormal immune response occurs in individuals who have alleles associated with innate and adaptive immune mechanisms that predispose to inflammatory bowel disease (IBD). Interleukin-1 receptor-associated kinase 4 (IRAK-4) involved in the pathway produces cytokines that initiate and maintain inflammation through Toll-like receptors and interleukin-1 receptors on the membranes of innate immune cells are stimulated with antigens. It was aimed to investigate whether IRAK-4 rs3794262 and rs4251481 polymorphisms predispose to IBD and the possible effects of these polymorphisms by examining these gene polymorphisms with the clinic and prognostic parameters of IBD.

Material and methods

Real-time PCR technique was used to detect IRAK-4 polymorphisms in 107 patients with IBD and 103 healthy controls.

Results

As a result of experimental studies, the frequency of occurrence of rs4251481 polymorphism related AG genotype (P = 0.029) and G allele (P = 0.005) was found to increase statistically in patients compared to controls. In the control group, the rs4251481 AA genotype rate of incidence increased compared with the patient group (P = 0.005).

Conclusion

Consequently, this is the first study in terms of both polymorphisms on IBD. These results suggest that rs4251481 AG genotype and G allele are associated with increased IBD risk in patients.

Identification and functional characterization of IRAK-4 in grass carp (Ctenopharyngodon idellus)

IL-1R-associated kinase 4 (IRAK4), a central TIR signaling mediator in innate immunity, can initiate a cascade of signaling events and lead to induction of inflammatory target gene expression eventually. In the present study, we cloned and characterized an IRAK4 orthologue from grass carp (Ctenopharyngodon idella). The full length cDNA of CiIRAK4 was 2057 bp with an ORF of 1422 bp encoding a polypeptide of 472 amino acids. Multiple alignments showed that IRAK4s were highly conserved among different species. Phylogenetic tree analysis revealed that CiIRAK4 shared high homologous with zebra fish IRAK4. Expression analysis indicated that CiIRAK4 was widely expressed in all tested tissues. It was significantly up-regulated after treatment with poly I:C, especially obvious in liver and spleen. Also, CiIRAK4 could be induced by poly I:C and LPS in CIK cells. Fluorescence microscopy assays showed that CiIRAK4 localized in the cytoplasm. RNAi-mediated knockdown and overexpression assays indicated that CiIRAK4 might have little effect on NF-kappa B p65 translocation from cytoplasm to nucleus, indicating that CiIRAK4 was dispensable for activation of NF-kappa B p65. In addition, IRAK4 promoted IRF5 nuclear translocation, which has nothing to do with the interaction between IRAK4 and IRF5. It suggested that fish IRAK4 kinase regulated IRF5 activity through indirect ways.

Identification, characterisation and preliminary functional analysis of IRAK-M in grass carp (Ctenopharyngodon idella)

Interleukin-1 receptor-associated kinase (IRAK) family members play important roles in myeloid differentiation primary response 88 (MyD88)-dependent toll-like receptor (TLR) signaling, the crucial innate immune pathway in vertebrates. In the present study, the IRAK family gene IRAK-M (also called IRAK3) from grass carp (Ctenopharyngodon idella) was cloned and characterised. IRAK-M was mainly enriched in the spleen, and the significantly altered expression was observed after grass carp reovirus (GCRV) infection. Subcellular localisation showed that IRAK-M protein distributed uniformly in the entire cell and co-localised with MyD88 in the cytoplasm of transfected cells. Additionally, the interaction between IRAK-M and MyD88 was confirmed by bimolecular fluorescence complementation (BiFC) system. Moreover, deficient of IRAK-M in C. idella kidney cell line (CIK) with small interference RNA (siRNA) upregulated polyinosinic:polycytidylic acid (poly(I:C))-induced inflammatory cytokines production, including interleukin 8 (IL-8), IL-6, and tumour necrosis factor α (TNF-α), which reveals that IRAK-M functions as a negative regulator of inflammatory cytokines. Taken together, our results demonstrate that IRAK-M gene plays an important role in innate immune regulation and provide new insights into understanding the functional characteristics of the IRAK-M in teleosts.

Effect of high fat diet on NF-кB microRNA146a negative feedback loop in ovalbumin-sensitized rats

The present study aimed to investigate the role of microRNA-146a and its adapter proteins [interleukin-1 receptor-associated kinase 1 (IRAK1) and tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6)] in the pathogenesis of ovalbumin (OVA)-sensitized rats in association with the diet-induced obesity condition. Twenty male Wistar rats were divided into four groups: control with normal diet (ND), OVA-sensitized with normal diet (S + ND), high-fat diet (HFD), and OVA-sensitized with high-fat diet (S + HFD). All the animals were fed for 8 weeks with standard pelts or high-fat diet, and were then sensitized and challenged with OVA or saline for another 4 weeks. The tracheal responsiveness to methacholine, serum protein levels, and lipid profile levels was measured by the ELISA method. Moreover, the gene expression level of microRNA-146a (miR-146a) was measured in the lung tissue of the rats using the real-time PCR method. Maximum response to methacholin increased in the S + HFD group in compared with ND, S + ND, and HFD groups (P < 0.05 to P < 0.001). Moreover, in the S + HFD group the mRNA expression levels of miRNA-146a increased in the lung tissue (P < 0.001). In addition, the protein analysis results showed that IRAK1, TRAF6, NF-kB, and IL-1β protein levels were high in the S + HFD group compared to the ND and HFD groups; however, in compared with the S + ND group, only the IL-1β protein level was higher in the S + HFD group (P < 0.05). These results suggest that a defect in the NF-kB-miR-146a negative feedback loop may be involved in the pathogenesis of obesity associated with OVA-sensitized condition. © 2018 BioFactors, 45(1):75-84, 2019.

A novel interleukin-1 receptor-associated kinase-4 from thick shell mussel Mytilus coruscus is involved in inflammatory response

Interleukin-1 receptor-associated kinase-4 (IRAK4) is considered as the most upstream kinase of IRAKs and plays a vital role in Toll-like receptor/Interleukin-1 receptor (TLR/IL-1R) signal transduction. In the present study, IRAK4 from thick shell mussel Mytilus coruscus (McIRAK4) was identified and characterized. McIRAK4 showed the most similarity to its counterparts in bivalves. The conserved death domain (DD) and catalytic domain of serine/threonine kinases (STKc) were predicted in all examined IRAK4s. McIRAK4 transcripts were constitutively expressed in all examined tissues with the higher expression level in immune related tissues, and were significantly induced in haemocytes upon lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid (poly I:C) challenge. Further, the expression of McIRAK4 was obviously repressed by dsRNA mediated RNA interference (RNAi), meanwhile the proinflammatory cytokines TNF-alpha and IL17 were down-regulated while the antiinflammatory cytokine TGF-β was up-regulated. Additionally, McIRAK4 showed a global cytoplasmic localization in HEK293T cells through fluorescence microscopy. These results collectively indicated that McIRAK4 is one member of IRAK4 subfamily and might play the potential signal transducer role in inflammatory response. The present study provides supplement for TLR-mediated signaling pathway triggered by pathogenic invasions in thick shell mussel, and contributes to the clarification of the innate immune response in molluscs.

Identification and functional characterization of three myeloid differentiation factor 88 (MyD88) isoforms from thick shell mussel Mytilus coruscus

Myeloid differentiation factor 88 (MyD88) is a pivotal adapter protein that involved in interleukin-1 receptor/toll-like receptor (IL-1R/TLR) signal transduction, which could spur downstream cascades and eventually drawn into innate immune response. MyD88 has been extensively studied in vertebrates, however, the information ascribe to MyD88 in invertebrates is still very scarce especially its function annotation remains extremely obscure. At here, three novel MyD88 isoforms termed McMyD88a, McMyD88b and McMyD88c were firstly cloned from thick shell mussel Mytilus coruscus. McMyD88a, McMyD88b and McMyD88c shared domain topology containing the Death domain (DD) and TIR domain (TIR) with its counterparts in mammals. All three McMyD88s were ubiquitously expressed in examined tissues in thick shell mussel, with the higher expression levels in immune-related tissues such as haemocytes, gills and digestive glands. Upon Vibrio alginolyticus, polyinosine-polycytidylic acid (poly I:C) and lipopolysaccharide (LPS) challenge, McMyD88a, McMyD88b and McMyD88c transcripts were significantly induced in haemocytes despite of differential expression levels and responsive time points. Overexpression of McMyD88a, McMyD88b and McMyD88c showed a dose-dependent induction to NF-κB or ISRE in mammalian cell lines. Taken together, these results suggested that McMyD88a, McMyD88b and McMyD88c are members of MyD88 family and play potential roles in innate immune response to pathogenic invasions in thick shell mussel. Moreover, these results suggested indirectly the existence of a MyD88-dependent signaling pathway in thick shell mussel, and provide insight into the immunoregulatory effect in molluscs.

Genetic variant of IRAK2 in the toll-like receptor signaling pathway and survival of non-small cell lung cancer

The toll-like receptor (TLR) signaling pathway plays an important role in the innate immune responses and antigen-specific acquired immunity. Aberrant activation of the TLR pathway has a significant impact on carcinogenesis or tumor progression. Therefore, we hypothesize that genetic variants in the TLR signaling pathway genes are associated with overall survival (OS) of patients with non-small cell lung cancer (NSCLC). To test this hypothesis, we first performed Cox proportional hazards regression analysis to evaluate associations between genetic variants of 165 TLR signaling pathway genes and NSCLC OS using the genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). The results were further validated by the Harvard Lung Cancer Susceptibility GWAS dataset. Specifically, we identified IRAK2 rs779901 C > T as a predictor of NSCLC OS, with a variant-allele (T) attributed hazards ratio (HR) of 0.78 [95% confidence interval (CI) = 0.67-0.91, P = 0.001] in the PLCO dataset, 0.84 (0.72-0.98, 0.031) in the Harvard dataset, and 0.81 (0.73-0.90, 1.08x10-4 ) in the meta-analysis of these two GWAS datasets. In addition, the T allele was significantly associated with an increased mRNA expression level of IRAK2. Our findings suggest that IRAK2 rs779901 C > T may be a promising prognostic biomarker for NSCLC OS.

Molecular identification and functional characterization of IRAK-3 from a teleost fish, the orange-spotted grouper (Epinephelus coioides)

Interleukin-1 receptor-associated kinase-3 (IRAK-3) is a unique IRAK family member, which negatively regulates the TLR-mediated immune response in mammals. However, the function of IRAK-3 remains to be elucidated in fish. In the present study, an IRAK-3 cDNA sequence (EcIRAK-3) with an ORF of 1776 bp encoding 591 amino acids was identified in the orange-spotted grouper (Epinephelus coioides). Sequence analysis indicated that EcIRAK-3 shared the conserved structure characteristics and functional sites of vertebrate IRAK-3, and has a high sequence identity and phylogenetic relationship with that of other fish species. The genomic EcIRAK-3 ORF contained 13 exons and 12 introns, which was similar to that of most other fish species. In healthy grouper, EcIRAK-3 was ubiquitously expressed in seven tested tissues with the highest expression in the gills. Following Cryptocaryon irritans infection, the EcIRAK-3 transcript was up-regulated in the gills during the course of the experiment, but down-regulated in the spleen at an earlier point in time. EcIRAK-3 was localized in both the cytoplasm and nucleus in a condensed form, and its cellular distribution was affected by the death domain and ProST domain. In addition, EcIRAK-3 significantly increased MyD88-mediated NF-κB activity, and its function was ProST domain and kinase domain dependent. Taken together, the results obtained here have contributed to the understanding of the function of IRAK-3 in fish.

Globular Adiponectin Exerts a Pro-Inflammatory Effect via IκB/NF-κB Pathway Activation and Anti-Inflammatory Effect by IRAK-1 Downregulation

Adiponectin, a hormone produced by adipose tissue, is very abundant in plasma, and its anti- and pro-inflammatory effects are reported. However, the mechanisms of these pro- and anti-inflammatory effects are not fully defined. Herein, we evaluated the dual inflammatory response mechanism of adiponectin in macrophages. Short-term globular adiponectin (gAd) treatment induced IκBα degradation, NF-κB nuclear translocation, and TNF-α production in RAW 264.7 cells. Polymyxin B pretreatment did not block gAd-induced IκBα degradation, and heated gAd was unable to degrade IκBα, suggesting that the effects of gAd were not due to endotoxin contamination. gAd activated IKK and Akt, and inhibition of either IKK or Akt by dominant-negative IKKβ (DN-IKKβ) or DN-Akt overexpression blocked gAd-induced IκBα degradation, suggesting that short-term incubation with gAd mediates inflammatory responses by activating the IκB/NF-κB and PI3K/Akt pathways. Contrastingly, long-term stimulation with gAd induced, upon subsequent stimulation, tolerance to gAd, lipopolysaccharide, and CpG-oligodeoxynucleotide, which is associated with gAd-induced downregulation of IL-receptor-associated kinase-1 (IRAK-1) due to IRAK-1 transcriptional repression. Conclusively, our findings demonstrate that the pro- and anti-inflammatory responses to gAd in innate immune cells are time-dependent, and mediated by the activation of the IκB/NF-κB pathway, and IRAK-1 downregulation, respectively.

Identification of a Constitutively Active Mutant Mouse IRAK2 by Retroviral Expression Screening

To identify the importance of IRAK2 kinase activity in TLR-mediated signaling pathways, we constructed a retroviral vector harboring either a mouse IRAK2 gene (IRAK2-WT) or with its mutant with loss of function of its ATP-binding site (IRAK2-KD). Further, we comparatively analyzed for the gain of function and modulations in TLR-mediated signaling pathways in IRAK2 knockout (IRAK2-KO) macrophages upon introduction of the IRAK2-WT retroviral constructs. The pBS/IRAK2-KD with the ATP-binding site mutation in IRAK2 was obtained by using site-specific mutagenesis. The recombinants were identified with appropriate double digestion and sequence analysis. The recombinant vector constructs were transfected by lipofection into phoenix packaging cells. The viral vectors (10⁷ cfu/mL) with the construct were allowed to infect IRAK2-KO macrophages. The results showed that IRAK2-WT gene overexpressed in the IRAK2-KO macrophages exhibited a modified IRAK2 expression upon LPS induction. However, the modification was absent with IRAK2-KD construct on LPS stimulation; instead, the IRAK2 protein stability was reduced considerably. The results further show that the LPS-induced effect on the stability of IRAK2 is dependent of IRAK4 stimulation.

Protective Effects of a Lipid Extract from Hard-Shelled Mussel (Mytilus coruscus) on Intestinal Integrity after Lipopolysaccharide Challenge in Mice

This study investigated the protective effects of a lipid extract from hard-shelled mussel (HMLE) on intestinal integrity and the underlying mechanisms after a lipopolysaccharide (LPS) challenge in mice by using a 3 × 2 factorial design. Mice received olive oil, fish oil, and HMLE (n = 12 per group) by using gastric gavage for six weeks, respectively. Then half the mice in each group was injected intraperitoneally with LPS and the other half with phosphate buffered saline. Four hours after injection, mice were sacrificed and samples were collected. n-3 PUFAs were significantly enriched in erythrocytes following fish oil and HMLE supplementation. Both fish oil and HMLE improved intestinal morphology by restoring the ileac villus height and barrier function, which is indicated by decreased colonic myeloperoxidase activity and increased diamine oxidase activity as well as enhanced mRNA expression of intestinal tight junction proteins known as occludin and claudin-1 when compared with olive oil. In addition, both fish oil and HMLE increased colon production and the expression of anti-inflammatory cytokine, IL-10, while they inhibited the abnormal production and expression of pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6 relative to the olive oil. Lastly, in comparison with olive oil, both fish oil and HMLE downregulated the TLR-4 signaling pathway by reducing the expression of two key molecules in this pathway, which are called TLR-4 and MyD88. These results suggest that HMLE had a protective effect on intestinal integrity after the LPS challenge, which was equivalent to that of fish oil. This effect might be associated with the regulation of inflammatory mediators and the inhibition of the TLR-4 signaling pathway.